An in vitro clonal assay already shown to be useful in the study of other neoplasms will be directly applied to the study of bladder cancer. Urothelial cells, obtained by tumor biopsy and bladder barbotage, from bladder cancer patients will be exposed to cytotoxic agents in vitro. Subsequent reduction in the clonogenic capacity of these cells will be used as a measure of drug sensitivity of each patient's bladder cancer cells. In vitro drug sensitivity will be correlated with in vivo drug sensitivity for each patient specifically. We will ultimately use such information to develop an individualized predictive approach to the chemotherapy of transitional cell carcinoma. In addition, the differential ability of neoplastic and normal urothelial cells to form clonal aggregates will be examined in detail. Clonal aggregates from "normal" and bladder cancer patient will be examined by means of light and electron microscopy, chromosomal studies and ABO antigenic studies with the aim of developing a specific and sensitive indicator of the biologic potential of the urothelium.